Construction waste minimisation comparing conventional and precast construction (Mixed System and IBS) methods in high-rise buildings: A Malaysia case study

The construction industry has always been a major generator of construction waste and is often faced with the issue of its effective management in minimising environmental pollution. This research paper focuses on the construction waste generated from the construction of high rise buildings using 3 construction methods; Conventional Construction (Category I), the Mixed System (Category II) and Industrialised Building System (IBS, Category III). The construction waste for each construction category were characterised into its mineral and non-mineral components. The construction waste usage efficiency (CWUE), waste generation, reuse and recycling rates were also calculated. The IBS (Category III) was found to be the most efficient construction method with a waste generation rate (WGR) of 0.016 tons of construction waste/m2 floor space compared to the Mixed System (Category II) at 0.030 tons/m2 and the Conventional Construction (Category I) at 0.048 tons/m2. The construction waste usage efficiency (CWUE) was the highest in Category III (IBS) at 94.1% with only 5.9% of the total construction waste in this category being disposed at landfills. The Construction Industry Development Board (CIDB) of Malaysia has recognised its benefits and has actively promoted the use of IBS in Malaysia. The waste characterisation data and its uses (reuse and recycling) obtained from this study could be used as baseline data to promote and encourage the Malaysian construction industry to adopt the use of precast technology, the Industrialised Building System (Category III) and move away from the more traditional resource hungry Conventional Construction (Category I). The inclusion of the Mixed System (Category II) in this study as an intermediate construction method was aimed at providing the link between the Conventional Construction (Category I) and the IBS (Category III). The Mixed System (Category II) incorporates both the IBS and Conventional Construction methods. The Conventional Construction (Category I) with the incorporation of new construction technologies could easily be reclassified as the Mixed System (Category II), allowing Malaysian contractors to easily adopt it. This paves the way for better understanding for the use of precast technology which eventually would result in a positive shift towards the use of the IBS (Category III) by Malaysian contractors in the future. Thus, improving the construction industry's environmental performance and commitment to sustainable development as outlined by the CIDB's Construction Industry Master Plan 2006–2015 for Malaysia.

► The lowest WGR was recorded in the IBS method at 0.016 tons of CW/m2 floor space.
► The Mixed System bridges the gap between Conventional Construction and IBS in waste management.
► Disposal preference for Conventional Construction was landfills.
► The Mixed System preferred recycling and IBS was reuse.